Fasteners, particularly screw type fasteners drive through and/or into two objects, securing them to one another. Subject to certain stresses due to vibrations, thermal expansion/contraction, pulling, or twisting, screw-type fasteners can loosen over time. Moreover, some fasteners, used to retain metal or plastic roofing or siding sheets to a support structure, such as wood framing, may loosen over time, compromising the seal between the fastener head and the sheet material. In some applications, such loosening can lead to serious problems.
Previous methods for preventing screws from backing out, especially in sheet metal screw applications include the use of a washer, in particular a flexible washer, that dampens vibration and secures the fastener to the objects being fastened.